1. Field of the Invention
This invention relates to sails for sailcraft and methods for their fabrication. More particularly, it concerns (1) new sail fabrication methods that eliminate operations in prior known methods, e.g., retabling to produce fair curves of luff, leech and foot, and (2) new forms of sails made from synthetic fiber cloth that cannot be altered in shape without detection to provide true onedesign racing in racing class sailboats.
The fabrication of sails for sailcraft has been practiced for centuries and can truly be classed as an art, i.e., each separate sail has been a separate work of the art of a particular sail maker. Hence, complete identity between sails has not been needed nor achieved in practice. Historically, these facts were of little or no concern to the users of sails, e.g., ancient workboat masters were interested in the strength and durability of their sails, not their identity with sails of another boat. Although wind is still used to a limited extend as the power for work-boats, the vast majority of extant sailcraft are used for pleasure, i.e., cruising and racing. Racing sailcraft dominate the field in terms of numbers and money spent in purchase and maintenance.
Modern racing sailcraft can be divided into several general classes, e.g., one-design, development and handicap. One-design boats are ideally supposed to be identical with each other in all respects as required by their class rules, e.g., hull dimensions, permitted equipment, etc.. In some one-design (OD) classes, sails may vary provided they do not exceed certain maximum limits, while in other OD classes the sails of all boats are supposed to be identical. A few OD classes have gone to the extent of restricting sails to those produced by one or a few selected sailmakers in an effort to achieve identity.
In the development classes, e.g., 12-meter yachts of "Americas Cup" fame and the International 14 dinghies, boats are open to variations of hull shape, sail configuration, etc., provided they conform to a formula that limits variable parameters in an interrelated manner. Such boats are raced as equals of one another, i.e., the first to finish wins. Measurements of boats and sails by skilled measurers are required to determine if they qualify and changes are either prohibited thereafter or, in some cases, permitted with remeasurement.
In the handicap classes, the boats may be built to any design of hull and size of sail. A handicap rating is then assigned to each boat by an official measurer calculated on a complex formula. In a handicap race, time allowances are given each yacht based on its rating, i.e., the first to finish is often not the winner. Recently, a variation of handicap racing was developed, i.e., so-called flat racing, as with 1/4 ton, 1/2 ton, 3/4 ton and 1 ton yachts, where handicap boats vary their sails, rigging, etc., so as to equal or approach a maximum rating for that class. In flat racing, all boats race as equals and the first to finish wins.
Sailing vessels are broadly divided into two types, i.e., fore-and-aft rigged and square-rigged. The former type may be further divided into those carrying gaff-headed mainsails and those carrying jib-headed or Marconi rig mainsails. The present invention is particularly relevant to fore-and-aft rigged vessels carrying jib-headed mainsails. Principle types of such boats are cat, sloop, cutter, yawl and ketch.
The new methods and products of this invention are pertinent to sails from all classes of racing sailcraft, including ice-boats, wheeled land-boats, as well as watercraft. However, the new methods and products have particular significance to one-design sailcraft.
There are literally thousands of different OD sailboat classes. They come and go, or fade in and out, as new designs are developed, old ones are changed to up-date them, etc.. There are a select few recognized by the International Yacht Racing Union (IYRU) for international competition, e.g., the Star class which is one of the oldest of the extant classes and widely sailed throughout the world. Only IYRU recognized boats are sanctioned for racing in the World Olympics and the present six olympic classes are:
Finn -- a 14 ft. single-handed, center-board cat boat. PA0 470 -- a 15 ft. two-man, center-board sloop. PA0 Flying Dutchman -- a 20 ft. two-man center-board sloop. PA0 Tempest -- a 22 ft. two-man, keel sloop. PA0 Soling -- a 26 ft. three-man, keel sloop. PA0 Toronado -- a two-man sloop-rigged catamaran.
The world population of such small OD boats is very much greater than the larger in-board auxiliary sail yachts which may be raced on the open ocean (so-called off-shore racing) as well as in protected waters to which the small OD classes are mostly restricted. The new methods and products described below are particularly pertinent to the small OD classes because of the need for mass production and cost savings to maintain expense of racing such boats to a minimum. However, they may also be used to advantage in connection with the larger off-shore type yachts.
2. Description of the Prior Art
A fore-and-aft rig sail, whether it be a mainsail or headsail, is designed to have draft, i.e., a bow or bulge in the leeward side when properly hoisted on the boat for which it is designed. This draft is obtained by creating a convex curve in the luff of the sail so that when the sail is hoisted on its mast, usually straight or at least less curved than the sail luff, the mast forces the cloth from its curvature back into the sail to produce the draft. By then bending the mast forward in the center portion, some of the draft can be removed and this is frequently done on OD boats when required to adjust for change in wind strength.
The leech of a sail may be cut in a straight line, but more often it is also cut on a convex curve to provide roach, an excess of cloth usually supported for proper shape by battens. Roach adds extra sail area and usually assists a mainsail to produce weather helm.
The luff and leech curves in a sail are created by edge shapes of the panels forming the sail. The shaped panels are fixed together by seams produced by broadseaming or seam tapering. The former produces a seam that varies in width along its length and is generally used in making one-off, large sails. The latter produces seams of substantially constant width. Regardless of the seam type used, the sail is formed of a plurality of panels cut from a bolt of cloth finished with straight parallel side edges formed by cutting off the selvage of the woven fabric. Up to the present, the edge of the cloth from the bolt has been used as one of the edges of the panels. Hence, in a four sided panel, only three edges would be severed to cut the panel from the bolt. If there is distortion in the edge of cloth when taken from the bolt, the final cut panels do not conform precisely to pattern. When a multiplicity of the same panels is cut from a pile of cloth sections for mass production of sails, dimension anomalies are increased. Consequently, sails have not previously been produced with the required luff and leech curves simply by cutting and seaming panels according to pattern. Thus, when the resulting cloth triangle is laid on a flat surface, the luff offsets are not then fair. Hence, a stick or other edging device is faired along marks in the luff, and a new luff is cut. The leech and foot are similarly faired in the operation known as retabling. The sail is then completed by putting on tapes, patches, luff rope, etc. There has been a need to improve on such known methods of making sails to eliminate the edge fairing after panel seaming and to eliminate dimension anomalies in the cutting of panels.
In most sail making, the joining together of the cloth panels involves simply seaming the panels on a sewing machine. However, it has been proposed to use adhesive to temporarily secure panels together to form a sail kit for subsequent stitching by the purchaser of the kit (see U.S. Pat. No. 3,459,149). Also, adhesive has been used in place of stitching to fix racing numerals on sails.